Recent automobiles have more advanced and various functions. Accordingly, in order to improve the operability of a control unit thereof, a so-called multidirectional operation switch capable of performing a plurality of operations with one switch unit is used instead of a plurality of push button switches on a control panel in many cases.
For example, one of such multidirectional operation switches is disclosed in the Japanese Patent Unexamined Publication No. 2001-26671.
An example of such conventional multidirectional operation switches is described with reference to FIG. 5. FIG. 5 is a sectional side elevation of a conventional multidirectional operation switch.
With reference to FIG. 5, upper case 1 is formed of an insulating resin into a cylindrical shape. Upper case 1 has through-hole 1A and cylindrical guide portion 1C in substantially a center thereof. Through-hole 1A has upper support 1B that forms an angular edge at the bottom end of the inner circumference thereof.
Lower case 2 is formed of an insulating resin into substantially a plate shape. Lower case 2 covers the bottom of upper case 1. Lower case 2 further has a protrusion that protrudes like a hill on the bottom surface in substantially the center thereof. Along the outer periphery of the top surface of this protrusion, lower support 2B is provided.
Circuit board 3 has a plurality of conductive patterns (not shown) formed on top and bottom surfaces thereof. On the top surface of circuit board 3, four push button switches 4A, 4B, 4C and 4D are radially disposed in four positions on a circle having a center at the center of central circular hole 3A. Respective push switches 4A, 4B, 4C, and 4D work as switch contacts in which depressing operations establish or break electrical contact with tactile feedback.
Lower support 2B of lower case 2 penetrates through circular hole 3A in circuit board 3 and protrudes upwardly. Circuit board 3 is fixed to lower case 2 by screws 102 through bosses 2D. Further, leads (not shown) connected to one end of circuit board 3 are led out of the multidirectional switch and electrically connected to electronic circuits (not shown) of an automobile.
Rocking body 6 is formed of an insulating resin into a shape substantially like a cylindrical shaft, and is disposed above circuit board 3. Rocking body 6 has spherical contact portion 6A disposed upwardly in the vicinity of the bottom end of the rocking body, and bearer portion 6B protruding downwardly. Contact portion 6A is supported by upper support 1B of upper case 1 to be capable of rocking. Similarly, bearer portion 6B is supported by lower support 2B of lower case 2 to be capable of rocking. Further, a plurality of depressing parts 6C, 6D, 6E, and 6F radially project from the bottom end of contact portion 6A to correspond with push button switches 4A, 4B, 4C, and 4D disposed on circuit board 3, respectively. The bottom surfaces of the tips of depressing parts 6C through 6F are in contact with corresponding push button switches 4A through 4D.
Operating shaft 6G extends from the top end of contact portion 6A, penetrating through through-hole 1A of upper case 1, and projects upwardly. Between the bottom end of lower support 2B of lower case 2 and the root of depressing parts 6C through 6F of rocking body 6, coil spring 7 made of a metal wire is disposed in a slightly elongated manner to urge rocking body 6 upwardly.
Additionally, operating body 8 has operating parts 8A through 8D on the upper surface thereof that are disposed to correspond with depressing parts 6C through 6F of rocking body 6, respectively. The top end of operating shaft 6G is fixed to the bottom surface of bowl-shaped operating body 8 by machine screw 104 or the like.
The multidirectional operation switch is structured as above. In the above structure, operating body 8 is depressed in a given direction. When operating part 8A at the right end, for example, is depressed downwardly, contact portion 6A of rocking body 6 urged upwardly by coil spring 7 rocks in a rightward direction together with operating body 8, while the contact portion is in contact with upper support 1B. At this time, depressing part 6C depresses push button switch 4A. This establishes or breaks electrical contact of push button switch 4A with tactile feedback. The electrical contact signal of push button switch 4A is transferred to the electronic circuits of an automobile outside of the multidirectional switch via leads on circuit board 3.
Similarly, when operating part 8B at the left end of operating body 8 is depressed downwardly, depressing part 6D on the left side depresses push button switch 4B. This establishes or breaks electrical contact of push button switch 4B with tactile feedback. Further, when operating part 8C or 8D in the forward or backward direction is depressed downwardly, depressing part 6E or 6F depresses push button switch 4C or 4D, respectively. This establishes or breaks electrical contact of each switch.
At this time, rocking body 6 is urged upwardly by coil spring 7. Then, contact portion 6A of rocking body 6 is brought into contact with upper support 1B along a line or at a point. Because there is a gap between bearer portion 6B and lower support 2B, rocking body 6 rocks in a direction of depression with jerky movement when one of operating parts 8A through 8D of operating body 8 is depressed downwardly against the urging force of coil spring 7.
Additionally, push button switches 4A through 4D perform contact operations with tactile feedback when operating body 8 is depressed. At this time, because rocking body 6 is urged upwardly by coil spring 7 at the root of depressing parts 6C through 6F, the tactile feedback obtained through operating body 8 is poor.
As described above, the conventional multidirectional operation switch tends to cause jerky movement and provide poor tactile feedback during operation. For these reasons, when a user operates the switch, while driving an automobile, it may be difficult for the user to operate the switch properly and recognize whether the user has performed a given operation positively. In other words, in some cases, a user cannot obtain a positive feel of operation.